Woodwind musical instruments, e.g., saxophones and clarinets, and other devices such as bird calls, utilize the vibration of a reed in response to a flow of air to generate a tone. These reeds include natural cane reeds and synthetic reeds. Tone generation in general depends on proper reed vibration. The reed is typically placed in contact with a mouthpiece to cover an opening or window. The reed is held in place by an adjustable clamp or ligature that surrounds the mouthpiece and the reed. Variations in the mouthpiece and ligature affect the vibration of the reed and, therefore, the performance or tone of the device or instrument.
The essential function of the mouthpiece of a woodwind instrument is to provide support for the reed over an aperture that allows the reed to vibrate and to direct the energy from the reed vibration through the aperture and into the bore of the instrument. The function and performance of a mouthpiece is influenced by the arrangement and geometry of the facing around the aperture as well as the tone chamber below the reed, which defines the route from the aperture to the bore. The tone chamber is conventionally formed as a rectangular box having straight interior walls and a flat generally rectangular bottom surface. The transitions from the top surfaces to the interior walls and from the interior walls to the bottom surface are right angles. The facing is conventionally a flat surface on the mouthpiece surrounding the aperture, and the reed is placed in contact with this flat surface, covering the aperture. The facing includes the aperture, called a window, and the window is surrounded by a table on one end, two side rails extending from the table and a tip rail opposite the table. The reed functions as a reed valve during vibration, opening and closing the window.
Unlike pianos, guitars, and similar musical instruments where the pitch of each note is precisely fixed, woodwind instruments require greater playing proficiency to achieve an acceptable level of pitch accuracy. Often, even after many years of study, many players are not able to satisfactorily produce good intonation absent significant effort. This problem is especially severe in hard rubber type mouthpieces. Hard rubber mouthpieces have a standardized external configuration that, in particular, is favored in the school-band venue. A major cause of the problem is the configuration of the window into the tone chamber that exists at the rear of the window in the standard configuration. The standard configuration produces, during operation, a shock front that tends to partially acoustically decouple the reed from the air column in the instrument. This permits the reed's own resonance to influence the air column resonance with regard to pitch. Therefore, if the reed's resonances are not directly or harmonically related to that of the air column, on a specific note, the air column frequency is pulled from the ideally produced frequency, causing the note to be out of tune. An accomplished player can correct this by way of nuanced changes in the position and pressure of the lip on the reed. However, if the effort to accomplish this can be reduced, the player can achieve the desired tone with less effort.
A conventional standard hard rubber woodwind mouthpiece has a geometry that transitions the rectangular geometry of the tone chamber to the circular central mouthpiece bore, often with an offset or abrupt change in cross-sectional geometry. In addition, the transition from the rear of the window to the table is either straight across the mouthpiece or has a slight round curvature. This transition creates an abutment at the rear of the window, resulting in an abrupt and generally flat surface. This abrupt change creates an impedance discontinuity. Anytime a discontinuity exists in an acoustic environment a shock front is created that causes reflections in two directions. This effectively creates a degree of isolation of one section of the vibrating air column from the opposite section. In a woodwind instrument this causes the coupling of the air column to the reed to be reduced, allowing the reed's resonances to influence the pitch. Therefore, a mouthpiece geometry is desired that eliminates this abrupt flat surface at the interface between the window and the table and provides tapered transitions from the sides walls and bottom surface of the tone chamber into the central bore of the mouthpiece.